*Updates are underlined

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.

Unit 1 (Shut down) 
- Explosive sound and white smoke were confirmed after the big quake 
  occurred at 3:36 pm on March 12. It was assumed to be hydrogen explosion.
- At approximately 2:30 am on March 23, seawater injection to the reactor 
  through the feed water system was initiated.
- From 3:37 pm on March 25, we started injecting freshwater. We are now 
  injecting freshwater by a motor driven pump powered by the off-site 
  transmission line at 6 m3/h.
- As it is suspected that hydrogen gas is accumulated inside Primary 
  Containment Vessel, we commenced the valve opening operation concerning 
  injection of nitrogen gas into the primary containment vessel at 10:30 
  pm April 6 and commenced injection at 1:31am April 7.

Unit 2 (Shut down) 
- At approximately 6:00 am on March 15, an abnormal noise began emanating 
  from nearby Pressure Suppression Chamber and the pressure within the 
  chamber decreased. 
- From 10:10 am on March 26, we started injecting freshwater to the reactor 
  and are now injecting freshwater by a motor driven pump powered by the 
  off-site transmission line at 7 m3/h.

Unit 3 (Shut down) 
- Explosive sound and white smoke were confirmed at approximately 11:01am 
  on March 14. It was assumed to be hydrogen explosion.
- From 6:02 pm on March 25, we started injecting fresh water to the reactor 
  and are now injecting fresh water by a motor driven pump powered by the 
  off-site transmission line.
- At 4:53 pm on May 12, as a part of work to switch the water injection 
  line to the reactor from the fire extinction system to the reactor feed 
  water system, we started water injection through the reactor feed water 
  system in addition to through the fire extinction system. 
- On May 23rd, we changed the rate of water injection to Unit 3 through 
  the fire extinction system piping arrangement from approximately 4 m3/h 
  to approximately 3 m3/h at 5:19 pm. The current rate of water injection 
  is approximately 3 m3/h through the fire extinction system piping 
  arrangement and approximately 12 m3/h through the reactor feed water 
  system piping arrangement.

Unit 4 (Outage due to regular inspection) 
- At approximately 6:00 am on March 15, we confirmed the explosive sound 
  and the sustained damage around the 5th floor rooftop area of Reactor 
  Building.
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel happened.

Unit 5 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 5:00 am on March 19, we started the Residual Heat Removal System Pump 
  (C) in order to cool the spent fuel pool.
- At 2:30 pm on March 20, the reactor achieved cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel happened.

Unit 6 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 10:14 pm on March 19, we started the Residual Heat Removal System 
  Pump (B) of Unit 6 in order to cool the spent fuel pool.
- At 7:27 pm on March 20, the reactor achieved cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel happened.

Operation for cooling the spent fuel pools 
- On May 23rd, from 4:00pm to 7:09pm we sprayed water to the spent fuel 
  pool of Unit 4 by the concrete pumping vehicle (from 2:17 pm to 2:37 pm, 
  we sampled, on a trial basis, radioactive materials in the ambient air 
  at the opening of the Reactor Building. We added hydrazine from 4:08pm 
  to 6:30pm). 
- We will continuously conduct further water spray depending on the 
  conditions of spent fuel pools, if needed.

Others 
- At 1:30 pm on April 26, we started spraying the dust inhibitor inside 
  the site.
- At 10:08 am on April 19, we started transfer of high level radioactive 
  wastewater from the vertical shaft near the turbine building of Unit 2 
  to the Centralized Radiation Waste Treatment Facility.
- At 2:00 pm on May 1, we started transferring the accumulated water in 
  turbine building of Unit 6 to temporary tanks.
- At 11:00 am on May 10, we started transferring the accumulated water 
  from the underground level of reactor building to the radiation waste 
  treatment facility of Unit 6.
- At 6:04 pm on May 17, we started transfer of high level radioactive 
  waste water from the underground level of the turbine building of Unit 
  3 to the Centralized Radiation Waste Treatment Facility.
- We will continue to take all measures to ensure the safety and to 
  continue monitoring the surrounding environment around the power station.